Most trailer hitches have a single hitch ball designed to fit with a particular sized trailer coupler. If it is desired to tow trailers having different sized couplers then the conventional one ball hitch cannot be used with these other sized couplers. In order to get around this problem, bumper plates have been provided with three holes, however only one of these holes is at the center of the vehicle while the other two holes are off center and provide an off center pull of the trailer. This increases the danger of sway action on the trailer particularly on slippery roads, resulting in jacknifing of the trailer and rendering the braking sytem ineffective.
I have developed, what I refer to as a spinning trailer hitch as covered in my Canadian Patent 1,216,316. The concept of my earlier patented trailer hitch, i.e. a hitch spinable to preset the required ball size on the line of pull of the hitch has substatial benefits over the conventional arrangements described immediately above. An arrangement similar to my own patented structure is also covered in U.S. Pat. No. 4,456,279 dated June 26, 1984 to Dirck.
Both the Dirck structure as well as my own earlier patented structure do however suffer from a common drawback. More particularly, there is no support from the bumper mount to the hitch plate directly at the hitch ball used for the towing. According to my own earlier patent as well as the Dirck patent, the hitch ball in use sits out over the bumper mount unsupported from beneath. The Dirck structure suffers from the further drawback that it relies on a single rotation preventing pin which is off line of the pulling axis of the hitch. Therefore, there are extremely high sheering pressures placed on this pin which, if not actually broken, is likely to jamb in position making it almost impossible to remove by hand from the Dirck trailer hitch.